The box structure with pointers
type box_type
integer :: m1, m2, m3, n1, n2, n3
integer :: nghost1, nghost2, nghost3
integer :: itime
integer :: ngrav, nquc, nBc, nBb
real :: time
real, pointer, dimension(:) :: xc1, xc2, xc3
real, pointer, dimension(:) :: xb1, xb2, xb3
real, pointer, dimension(:,:,:) :: rho, ei, v1, v2, v3
# if (rhd_box_grav01 == 1)
real, pointer, dimension(:,:,:) :: phic_grav
# endif /* rhd_box_grav01 */
real, pointer, dimension(:,:,:,:) :: quc
real, pointer, dimension(:,:,:) :: Bc1, Bc2, Bc3, Bb1, Bb2, Bb3, &
flux_B12, flux_B13, flux_B21, &
flux_B23, flux_B31, flux_B32
logical, pointer, dimension(:,:,:) :: entropy_switch
end type box_type